Alkylation process



Sept. 11, 1945. F. E. FREY ALKYLATION PROCESS Filed Feb. 7, 1942Patented Sept. 1l, 1945 ALKYLATION PROCESS Frederick E. Frey,Bartlesville, mila., assigner to y Phillips Petroleum Com Delaware pany,a corporation of Application February 7, 1942, Serial No. 429,962

A 7 Claims.

This invention relates to a process for the conversion, by an alkylationreaction in the presence of a liquid catalyst, of relatively low-boilinghydrocarbons to higher-boiling hydrocarbons. More particularly, itrelates to the efiicient utilization of a comparatively inerthydrocarbon stream containing a relatively small proportion of olefinsas a source of' olens for use as the alkylating agent.

Prior to this invention, the feeds to practical hydrouoric acidalkylation processes have comprised relatively large proportions ofreactive ingredients; for example, the feed used for the alkylation ofisobutane with butylenes ordinarily contains a total of fty per cent ormore of isobutane plus butylenes. Heretofore, a feed having a relativelyhigh proportion of inert diluent material has required equipment ofexcessive size.

An object of my invention is to provide a relatively simple, low-costhydrocarbon-conversion process wherein a relatively inert fluid streamcontaining comparatively small proportions of olefin hydrocarbons may beutilized efficiently as a source of alkylating agent for convertingrelatively lowboiling hydrocarbons to higherboiling hydrocarbons.

A further object of my invention is the elimination of large volumes ofrelatively inert material from an alkylation process in an early step,thereby increasing the capacity of the equipment.

Further objects and advantages of my invention will be apparent from thefollowing description and the accompanying drawing.

Olen hydrocarbons are very soluble in concentrated or anhydroushydrofiuoric acid, and polymerization of olefms in concentratedhydroiiuoric acid occurs rapidly at atmospheric temperatures.Consequently, in the prior art of alkylation of hydrocarbons, there is atheory that the olens must not come in contact with hydrogen iuorideexcept in low concentrations of olefins and in the presence of a largeexcess of alkylatable material; that is, the oleiins or other alkylatingagents have usually been added slowly with vigorous agitation to amixture comprising hydrogen fluoride and an alkylatable hydrocarbonunder alkylating conditions. I have found that, in a process foralkylating saturated hydrocarbons with olen hydrocarbons in the presenceof concentrated or anhydrous hydrofluoric acid, the olens can beadvantageously absorbed, under cert-ain specic conditions which will bedescribed hereinafter, by hydroiiuoric acid prior to contacting, underalkylating conditions, with an alkylatable hydrocarbon. The resultingacid (Cl. 260483A) solution, when used as an alkylating agent, producesin high yield a product of high octane number suitable for use asaviation-grade motor fuel. I have found that objectionablepolymerization of the olefins absorbed in thehydrofiuoric acid isaverted effectively by controlling the acid-to-oleiin ratio, thetemperature, the acid concentration, and the period of residence of theolefin in the acid prior to thecontacting with an alkylatablehydrocarbon under alkylating conditions. Hence, by the process of theinvention disclosed herein, hydrocarbon streams comprising relativelysmall proportions of olefins may be utilized advantageously as a sourceof alkylating agent in a process for the conversion of relativelylow-boiling hydrocarbons to higher-boiling hydrocarbons.

Understanding of some aspects of my invention will be aided by referenceto the accompanying drawing, which is a schematic ow-dia gram of onearrangement of apparatus for practicing the instant invention.

A liquid or liquefied hydrocarbon stream containing small proportions ofoleflns (for example, one toten per cent of propylene and/or butylenes)is admitted through inlet I I having valve I2 to mixing chamber I3,wherein it is contacted for a short time with concentrated hydroiiuoricacid, admitted through valve I4 and inlet I5, and/or valve I6 andconduit I'I. The mixer may be very simple; for example, a small chamberhaving several baffles, a length of pipe with or without bailies, asmall pump, or a small zone through which both streams are made to passat a high rate; in some cases, suilicient mixing and eiiicientabsorption of olens is obtained without a separate mixing apparatus bysimply passing the two streams through the same or closely adjacentinlets to a centrifuge or other separating means.

In the embodiment shown, the effluent from mixer I3 is passed by way ofconduit I8 to centrifuge I9, wherein it is separated into two liquidphases. 'I'he resulting hydrofluoric acid phase, which containsdissolved olefins, is forced as by gravity or by pump 23, throughconduit 24 and valve 25 to alkylator 26, wherein it is rapidly mixedwith a reactive paraiiin hydrocarbon, such as is'obutane or isopentane,admitted through conduit 21 having valve 28. Instead of centrifuge I 9,it is possible in some cases to use a simple separating tank whereinseparation is effected by gravity, or both centrifuge I9 and mixer I3may be replaced by a Podbielniak-type helical supercontactor. However,the arrangement shown of a small mixer and conventional centrifuge is vusually .preferred because the absorption and separation is accomplishedmuch more rapidly than could be done with a gravitational separator, andthe apparatus is simpler andless expensive than a Podbielniak-typecontactor.

The other or hydrocarbon phase from centrifuge I9 which contains smallproportions of organic fiuorides and dissolved hydrogen iluoride, ispassed via conduit 20 and valve 2| to acid washer 22. In this washer, itis distributed by suitable means 29 near the bottom of the washer, andit rises, by virtue of its relatively low density, countercurrently todownwardly iiowing substantially pure concentrated hydrofluoric acid,introduced near the middle of the washer through inlet 30, valve 3l, anddistributing means 32.k The organic uorides are absorbed from thehydrocarbon phase by the hydrofluoric acid, which, after a shortsettling period in space 33 at the bottom of the washer, is passedthrough valve I6 and conduit I1 for use vas olefin-absorbing liquid inmixer I3.

Although, as the hydrocarbon rises through the bottom half of washer 22,the countercurrently flowing concentrated hydrouoric acid eX- tractsorganic fiuorides, appreciable quantities of hydrofiuoric acid remaindissolved in th'e hydrocarbon. The hydrocarbon continues rising in theupper half of the washer, wherein it is contacted with acountercurrently owing aqueous phase, introduced as water or as a dilutesolution of 'hydrouoric acid of, up to about 40 per cent in strength,preferably a constant-boiling mixture, through valve 34, inlet 35, anddistributing means 35. The water or solution extracts the dissolvedhydrofluoric acid from the hydrocarbon phase. The hydrocarbon phase,after a short settling period in space 31 at the top of washer 22,wherein it is separated from the aqueous phase, is withdrawn throughoutlet 38 having valve 39; if desired, this material may be passed to afraotionator, not shown, to recover isobutane for alkylation.

The quantity of water or aqueous dilute hydrouoric acid introduced ispreferably about onetwentieth to one-tenth of the volume of hydrocarbontreated; a much larger proportion introduces excessive amounts of waterinto the system, whereas a much smaller proportion does not effectsubstantially complete recovery of hydrofluoric acid from thehydrocarbon. The quantity of -concentrated h'ydroiiuoric acid introducedat the middle of the washer preferably is from Aone-fourth to two timesthe volume of hydrocarbon treated, and should be at least five times thevolume of aqueous solution introduced at the top of the washer. Smalleramounts do not always completely remove alkyl uorides from thehydrocarbons or are diluted too much by the aqueous solution from thetop of the washer, whereas larger amounts produce an unnecessarily highrato of acid to hydrocarbon in the alkylator.

In some instances, when the concentration of olens in the feed isrelatively high, and/ or when the acid-to-olen is low, the temperatureof th'e extraction system is raised appreciably by the lheat of solutionof olefins in the hydrofluoric acid. Preferably, in such cases, coolingto about atmospheric temperature, to decrease the solubility of hydrogeniiuoride in the hydrocarbon layer, may be practiced. .A suitable coolingmeans, forexample, consists of one ormore coldwater coils situatedwithin mixer I3 and/or washer 22. l'

assaut Y The' preferred Vtime interval forpassage of olefins and:hydrogen uoride" from the inlet of mixer. i3, byr wayaof conduit I8,centrifuge la, pump 23, conduit-.24,an'd valvev 25, to the inlet ofalkylator'26 is`=intherange of 5 to 60 seconds; the preferredtemperature is in the range of 30 to 150 F.`; and the-preferred ratio ofhydrogen fluoride 'to'olen is inthe range of 10:1 to 50:1

by weight or more. These variables are mutually interdependent; forexample, at the lower temperature and the lower acid rate or longer timeinterval, approximately the same results are obtained as at high'ertemperatures and a higher acid rate or a shorter time interval. Goodresults can be obtained outside the ranges given, but these ranges arepreferred for practical reasons, as follows: The preferred timeintervals are obtainable with conventional equipment, especiallycentrifuging equipment, whereas shorter time intervals require morecostly equipment; the preferred temperatures are near atmospheric andare therefore obtainable with little or no refrigeration; the preferredacid-to-olen ratios are suitable for operation of the alkylation step.The exact optimum conditions for any particular case may be readilydetermined by trial.

In alkylator 26, under suitable` alkylating conditions, such as 30 to150 F., a pressure sumcient to maintain all components in the liquidphase, and for a time of about one to thirty or more mintues, theolefin-in-acid phase is agitated with an alkylatable hydrocarbon, suchas isobutane or isopentane, introduced through conduit 21 having valve28 in an amount of about two to ten times the amount of olen Aby weight.

The resulting mixture passes asthe eiiuent from aikylator 26 throughconduit 40 and valve 4l to separator '42, wherein, by cooling and/orgravitational or centrifugal means, it is separated into 40 two liquidphases.

cro

Of lthese phases, the lighter or hydrocarbon phase is passed by way ofconduit d3 and valve 4d to fractionation unit 45, in which it isseparated by fractional distillation into the following six fractions:(l) A relatively minor fraction of noncondensable gases, which isremoved through outlet 46 Yhaving valve 41; (2) a relatively minorfraction, comprising an azeotropic mixture of hydrogen uoride and lighthydrocarbons, such as propane or butane, which passes via valve Q8 andconduit 49 to separator 5B; (3) a. comparatively large fraction,comprising unreacted readily alkylatable hydrocarbons, such as isobutaneor isopentane, which is recycled via conduit 5I, pump 52, valve 53, andconduit 2l to alkylator 25; (4) a fraction comprising relativelydimcultly alkylatable hydrocarbons, such as normal butane, which iswithdrawn through outlet 54 having valve 55; (5) a substantial fractionof highlybranched paraiiinic reaction products boiling within thegasoline range, which is withdrawn .through outlet 56 having valve 51;and (6)y a high-boiling bottom fraction, comprising heavy polymers andother icy-products, which is with'- drawn through outlet 58 having valve59.

The heavier or hydrouoric acid phase from separator 42 is recycled tomixer I3 and/ or washer 22 by way of conduit 60 and valve 6I and/orvalve 6,2, respectively. Preferably, however, a part of it is passedthrough conduit 63 and valve 64 to acid-fractionation unit 65, whereinit is saparated into th'e following four fractions: (1)- A minorfraction, comprising an azeotropic mixture of hydroiiuoric acid andlow-boiling hydrocarbons, such as propane or butane, which is passedthrough conduit 66 having valve 61 to separator 50; (2) a major fractionof substani tially pure anhydrous hydrogen fluoride, which is recycledthrough conduit 68 and valve 89 and/or valve to washer 22 and/or mixerI3, respectively; 3) a fraction, comprising a constant-boiling mixtureof water and hydrogen fluoride, which is passed through conduit 1|,valve 12, and inlet 35 to the top of Washer 22, wherein it is used toextract HF from the olefindepleted hydrocarbon phase as alreadydescribed;

4) a bottom fraction, comprising hydrocarbon residue and high-boilingby-products, which is withdrawn through outlet 13 having valve 14. Ifdesired, any excess constant-boiling mixture may be withdrawn from thesystem, as through outlet 19 and valve 80, and this excess may betreated, in a separation step not shown,` for the recovery of hydrogeniiuoride. l I

Separator 50 is shown as a separation means, in which, by cooling andgravitational or centrifugal means, the azeotropic mixtures ofhydrouoric acid and low-boiling hydrocarbons from/ fractionators 45 and65 separate into two liquid phases; the lighter or hydrocarbon phase iswithdrawn through outlet having valve 16, and the heavier orhydrolluoric acid phase is passed by way of conduit 11 and valve 18 tofractionator B5. Alternatively, instead of going to separator 50, eitheror both of the azeotropic mixtures may be recycled to alkylator 26, -bymeans that are.

not shown but that can be readily supplied by those skilled in the art;this alternative is preferred when the low-boiling hydrocarbon in theazeotropic mixture is a relatively easily alkylatable hydrocarbon, suchas an isoparaiiin.

I have found that the rate of polymerization of olens in hydrofluoricacid is reduced considerably` if some water is present in the acid.However, although alkylation with hydrofluoric acid containing up toabout 10 per cent water produces in high yield a product of goodquality. both the quality and the yield may be somewhat inferior tothose obtained by alkylation with acid containing less Water. Therefore,it is advantageous to have a higher concentration of Water present inthe acid phase of the olefin-extraction step than in the acid phase ofthe alkylation step. This desirable end can be attained in amodification of my process in which the hydrofiuoric acid introduced inthe absorption step is of relatively phase. Preferably, therefore, sothat relatively low operating pressures may be used, the averageboiling-point of the olefin-containing feed is of the order of, orhigher than, that of butanes. The specic olelln in the feed, inaccordance with the prior art of hydrouoric afcid alkylation, ispreferably one having three to five carbon atoms per molecule or amixture of these. Although pure propylene is a relatively low-boilinghydrocarbon, it dissolves readily in, or is readily extracted from agaseous mixture by, relatively higher-boiling hydrocarbons, such asnormal butane, normal pentane, normal hexane, or the like. Thus, asolution of propylene in a higher-boiling hydrocarbon may beadvantageously used as a feed to the absorption step of this process,thereby eliminating the necessity for using a. high operating pressureto maintain propylene in the liquid phase.

To illustrate some of the many aspects of my invention, the followingspecific examples are given:

Example I A butane fraction containing 11.2 per cent of unsaturatedhydrocarbon is contacted, at 71 F. and at suiiiclent pressure tomaintain the liquid phase, with concentrated hydrofluoric acid in n fsmall mixer; the resulting mixture is centrifuged to separate out anacid phase containing dissolved olens, which is immediately passed to analkylator, and a hydrocarbon phase from' which, first, organic iiuorineis lrecovered by washing with countercurrently flowing concentratedhydroiiuoric acid, and, second, dissolved hydrogen fluoride is recoveredby washing with a countercurrently flowing aqueous solution of hydrogenfluoride. The eliiuent hydrocarbon stream is free from un-V saturatesand contains less than 0.002 per cent by 4 0 weight of organic iluorineand less than 0.02 per cent .by weight of dissolved hydrogen uoride. Theacid from the washing operations is added to the mixer, thus preventingthe loss of fiuorine as hydrogen fluoride or as organic iluorine in thehydrocarbons from which the olefins have been extracted. The totalaverage time of mixing,

lower concentration, such as to 90 per cent by Weight, the balance beingwater. and in which a proportion of substantially anhydrous hydrouoricacid large enough to raise the average concentration to the desiredvalue, at least to 90 per cent and preferably higher, is introduced inthe alkylation step. This modification is advantageous, for instance, ifmeans for carrying out the absorption and separation steps within thepreferred short time interval are not available. Usually', however, inorder to simplify the operation and to maintain a high acid-to-oleiinratio in the absorption operation, it is preferable to introduce all thehydrogen uoride, in concentration sufficient to obtain efficientoperation of the alkylation step, into the washing or mixing steps, andto depend upon control of the time, temperature, and acid-to-olefinratio to avert undesirable polymerization reactions.

The olefin-containing feed to the absorption step of this process shouldbe liquid, and the pressures and the temperatures in the mixing,centrifuging, and Washing equipment must be so controlled as to maintainall components in the liquid centrifuging, and introduction into thealkylator is about 15 to 30 seconds. The alkylating conditions are: F.,ve minutes contact time. pressure suicient to maintain the liquid phase.and rapid agitation with excess isobutane. The eliiuent from thealkylator is separated by gravity into an acid phase and a hydrocarbonphase. Half of the acid phase is recycled directly to the mixer.

and half is passed to an acid-fractionating unit. From this unit arewithdrawn a substantially anhydrous hydrofiuoric acid fraction and aconstant-boiling water-hydrogen fluoride fraction;

-these fractions are recycled to the first and second above-describedwashing operations, respectively. The hydrocarbon phase is fractionated.to recover lsobutane, which is recycled to the alkylator, and relativelyhigh-boiling hydrocarbons suitable for use as motor fuel.

The relative proportions of materials in the various steps are asfollows: Acid-to-olen ratio in mixer and centrifuge, 15:1;isobutane-to-olen ratio in feeds entering alkylator, 8:1; acid directlyrecycled from alkylator to mixer, 50 per cent; ratio of concentratedacid in rst washing operation to aqueous solution in second washingoperation, 8: 1.

'I'he yield of debutanized alkylate is about 167 per cent based on theweight of oleiins in the feed. Upon rerunning, 96 per cent of thisalkylate is obtained as an aviation-gasoline cut' having an octanenumber of 91, which is raised to about 100.2 by the addition oi one cc.of tetraethyl lead per gallon of gasoline.

Example II half times as much acid is used, of which onethird isintroduced in the washing steps and twothirds in the mixing step. Ayield of debutanized alkylate of 155 per cent by weight of unsaturatesin the feed is obtained. Upon rerurming, 9d per cent of 89 octaneaviationgasoline is obtained.

Itwill be evident to those skilled in the art that my invention eects asubstantial reduction in the size of equipment required for hydrofluoricacid alkylation, or a substantial increase in the capacity of existingplants. My invention' makes possible the recovery and utilization as'alkylating agent, of oleiins present only in small proportions, such asve per cent or even less, in hydrocarbon streams. My invention providesfor substantially complete recovery from the olenndepleted hydrocarbonstream of dissolved hydrogen fluoride.

Obviously, there are many variations and modifications of' my invention,only a few of which are described herein. For example, washer 22 may bereplaced by a series of washers in which the olefin-depleted hydrocarboneiiiuent from mixer i3 is contacted in succession with concentratedhydrouoric acid, one or more aqueous acid solutions in the order ofdecreasing concentration, and finally, if desired, pure water. An acideffluent from one washer may be used as the extracting liquid in awasher using a more concentrated solution of acid. The one or moreconcentrated acid extracts, which contain dissolved alkyl fluordes, maybe passed to mixer i3. If desired, the one or more dilute acid extracts,

,which are substantially pure aqueous solutions i of hydrogen fluoride,may be passed to a fractonating unit to be separated into aconstantboiling mixture, which may be recycled to theappropriate washer,and into the component in excess.

In another modification, part or all of the aqueous acid solutionintroduced into washer 22 through distributing means 36 may bewithdrawn, by means' not shown in the drawing, at a point :lust abovedistributing means 32, and may be recycledto distributing means 36 orpassed to an acid fractionator, such as fractionator B5, for separationinto 'substantially pure hydroiluoric acid and a maximum-boiling aqueoussolution. Fractionator 65 may be any system capable of producing theseparations indicated. 'It may, for example, comprise the following: Afirst column from which high-boiling organic material is withdrawn as akettle product and from which the overhead eiiluent is passed to aseparator for separation into two liquid phases; and a second column, inwhich the hydrofluoric acid ph'ase from this separator is fractionatedinto an overhead effluent of substantially anhydrous hydrofiuoric acidand a kettle product of a constant-boiling pumps, valves, fractionators,coolers, and the like, such as are well known in the art, may be usedwherever they are ,desirable or convenient. It is intended that theforegoing specinc examples and description of particularapparatusandoperatingconditions should illustrate the principles of myinvention and the preferred modes of practicing it, but that the scopeci the invention should be limited only by the following claims.

I claim:

l. In a process for alkylating a low-boiling isoparamn with alow-boiling olefin, the improvenient which comprises contacting anolefin-containing h'ydrocarbon mixture with liquid aqueous hydroiiucricacid having a hydrogen uoride concentration in the range of 65 to 90 percent by weight and with a ratio of hydrogen uoride to olefin of at least10:1 by weight, separating a resulting liquid hydrofiuoric acid phaseand a resulting hydrocarbon phase containing minor amounts of organicfiuorine compounds and free hydrogen duoride, successively contactingsaid separated hydrocarbon ph'ase with liquid hydroiiuoric acid toremove said organic fiuorlne compounds and with highly aqueoushydrofiuoric acid to remove free hydrogen fluoride, adding resultingextract phases to the lrst said aqueous hydrouoric acid, admixing withthe first said resulting liquid hydroiluoric acid phase suicienthydrogen fluoride to raise the hydrogen fluoride concentration to analkylating strength above 90 per cent by 4weight and also admixing alow-boiling isoparafiln, maintaining in an alkylation zone the resultingadmixture under alkylation conditions to effect an alkylation of saidisoparanlns with olens dissolved in said aqueous hydrouoric acid, andrecovering from eiliuents of said treatment a hydrocarbon fractioncontaining alkylated isoparains so produced.

2. The process of removing olens from a hydrocarbon material containinglow-boiling olefin and paramn hydrocarbons, which comprises contactingsuch an olefin-containing hydrocarbon mixture with liquid aqueoushydrofiuoric acid having a hydrogen fiuoride concentration in th'e rangeof to 90 per cent by weight and with a ratio of hydrogen fluoride toolefin of at least 10:1 by weight, separating a resulting liquidhydrofiuoric acid phase and a resulting hydrocarbon phase containingminor amounts of organicfluorine compounds and free hydrogen fluoride,successively contacting said separated hydrocarbon ,phase with liquidhydrouoric acid to remove said organic iluorine compounds and withhighly -aqueous hydrouoric acid to remove free hydrogen fluoride, andadding resulting extract phases to concentrated hydrofiuoric acid toform the aforesaid aqueous hydrogen fluoride having a concentration of65 to 90 per cent by weight and recovering as eiiluents of said processan olefinfree hydrocarbon material and an aqueous liquid hydrofluoricacid containing dissolved oleiins.

; 3. In a process for alkylating a low-boiling n i'soparaflin with a,low-boiling olefln, the improveaqueous hydroiiuoric acid, either or bothoi' which ment which comprises intimately contacting at d temperature inthe range of 30 to 150 F. an olefin-containing liquid hydrocarbonmixture with liquid aqueous hydrofiuoric acid having a hydrogen fluorideconcentration in the range of 65 tov 90 per cent by weight and with aratio of hydrogen fluoride to olefin in` the range of 10:1 to 50:1 byweight, separating a resulting liquid `hydrofluoric acid phase fromunabsorbed inert liquid hydrocarbons, admixing with said aqueoushydrouoric acid phase sufficient hydrogen uaser-,7st

oride .to raise the hydrogen fluoride concentration to above per cent byweight and also admixing a low-boiling isoparamn, maintaining in analkylation zone the resulting admixture under alkylation conditions toeffect an alkylation of said isoparamn with oleflns dissolved in saidaqueous hydroiuoric acid, and recovering from effluents of saidtreatment a hydrocarbon fraction containing ailryiated isoparaiins soproduced.

d. in a process for alirylating a low-boiling alttylatable hydrocarbonwith a inw-boiling olefin, the improvement which comprises contacting anoieiin-containing hydrocarbon mixture with liquid aqueous hydrouoricacid having a hydrogen fluoride concentration in the range of 65 to 90per cent by weight and with a ratio of hydrogen iiuoride to olefin of atleast :1 by Weight, separating a resulting liquid hydrofluoric acidphase and a resulting hydrocarbon phase containing minor amounts oforganic iiuorine compounds and free hydrogen fiuoride, successivelycontacting said separated hydrocarbon phase with liquid hydroduoric acidto remove said organic uorine compounds and with highly aqueoushydroiluoric acid to remove free hydrogen iiuoride, adding resultingextract phases to the first said aqueous hydroluoric acid, admixing withthe first said resulting liquid hydrofiuoric acid phase sumcienthydrogen fluoride to raise the hydrogen fluoride concentration to analkylating strength above 90 per cent by weight and also admixing alow-boiling alicylatable hydrocarbon, maintaining the resultingadmixture under alkylation conditions to effect an alkylation of saidalkylatable hydrocarbon with oleiins dissolved in said aqueoushydroiiuoric acid, and recovering from eiiuents of said treatment ahydrocarbon fraction containing alitylated hydrocarbons so produced.

5. In a. process for alkylating a low-boiling alirylatable hydrocarbonwith a low-boiling olefin, the improvement which comprises intimatelycontacting at a temperature in the range of 30 to 150 F. anolefin-containing liquid hydrocarbon mixture with liquid aqueoushydrofiuoric acid having a hydrogen uoride concentration in the range of65 to 90 per cent by weight and with a ratio of hydrogen fluoride tooleiln in the range of 10:1 to 50:1 by weight, separating a resultingdrocarbon fraction containing alkylated hydrocarbons so produced.

6. In a process for alkylating a low-boiling isoparailn with alow-boiling oleiin, the improvement which comprises intimatelycontacting at a temperature in the range of 30 to 150 F. anolencontaining liquid hydrocarbon mixture with liquid aqueoushydroiiuoric acid having a hydrogen fluoride concentration in the rangeof to 90 per cent by Weight and with a ratio of hydrogen iiuoride toolen in the range of 10:1 to 50:1 by weight, separating a resultingliquid hydrouoric acid phase from unabsorbed inert liquid hydrocarbons,admixing with said aqueous hydroiuoric acid phase sumcient hydrogenfluoride to raise the hydrogen uoride concentration to above per cent byweight' and also admixing a lowboiling isoparamn, maintainingin analkylation zone the resulting admixture under alkylation conditions toeiect an alkylation of said isoparaidn with olens dissolved in saidaqueous hydrouoric acid, the time interval between the initial mixing ofsaid olen-containing hydrocarbon mixture with said aqueous hydrofiuoricacid and introduction of the resulting aqueous hydrofiuoric acid phaseto said alkylation zone being between about 5 and about 60 seconds, andrecovering from eiiiuents of said treatment a hydrocarbon fractioncontaining alkylated isoparafns so produced.

'7. In a process for alkylating a low-boiling alkylatable hydrocarbonwith a low-boiling olefin, the improvement which comprises intimatelycontacting at a temperature in the range of 30 to 150 F. anolefin-containing liquid hydrocarbon miX- ture with liquid aqueoushydrofiuoric acid having a hydrogen iiuoride concentration in the rangeof 65 lto 90 per cent by weight and with a ratio of hydrogen uoride toolefin in the range of 10:1 to 50:1 by weight, separating a resultingliquid hydrouoric acid phase from unabsorbed inert liquid hydrocarbons,admixing with said aqueous hydrofiuoric acid phase sufficient hydrogenIiuoride to raise the hydrogen fluoride concentration `to above 90 percent by weight, and also admixing a low-boiling alkylatable hydrocarbon,maintaining in an alkylation zone the resulting admixture underalkylation conditions to effect an alkylation of said alkylatablehydrocarbon with olens dissolved in said aqueous Ahydroiiuoric acid, thetime interval between the initial mixing of said olefincontaininghydrocarbon mixture with said aqueous hydrouoric acid and introductionof the resulting aqueous hydrofluoric acid phase to said alkylation zonebeing between about 5 and about 60 seconds, and recovering fromeffluents of said treatment a hydrocarbon fraction containing alkylatedhydrocarbons so produced.

FREDERICK E. FREY.

